Forgotten manga

The story was like, destructive... As far as I remember, they live in a mansion. I remember something like Bazooka. Maybe robots are included.. The problem is, the manga was forgotten and I couldn't even remember what's the gender of the main character.. Just post what you have in mind. I think, that's a shounen.. maybe no love.. it's like killing people.. I'm sorry I can't give any further info..